Valves for closed enclosure such as, particularly, an inflatable enclosure, as is known, comprise elements which constitute a body foreign to the enclosure and, most often, a part of which projects outside of the enclosure. Valves for inflatable balloons comprising a bladder, as is known, in particular for balloons made of a bladder of hot-molded synthetic material, comprise an orifice provided for inflation of the bladder. This orifice is generally made in a device which constitutes a body foreign to the bladder and which must be fastened in the mold, prior to molding, so that the device is covered by the bladder and while taking care that the orifice intake and outlet are retained.
This device has the drawback of permitting only the inflation of the bladder and not its deflation. Further, the inflating process is delicate, so that the inflation of balloons is often performed at the factory. Because the balloons cannot be deflated, their transport and storage require considerable space.